Why storing renewable energy is critical

Everyone gets annoyed when their mobile phone battery dies at a pivotal moment. But some batteries are achieving a lot more for our lives, just in a less visible way. Emily McDaid pulls back the curtain on batteries that are a game-changer for our environment.

At Kilroot Power Station outside Carrickfergus, AES has a 10MW interconnected energy storage array. Using lithium ion batteries, AES’s Advancion proprietary technology stores energy when supply is high, to be used at times of peak demand.

Why is this important?

Renewable energy sources like wind and solar power aren’t available all the time but, as a nation, we need to keep the lights on. Having the ability to store energy created through renewables, to deliver a consistent level of supply into the grid, is the crux of the question of how to make renewables a profitable enterprise.

“The batteries went live on January 5th of [2016],” said Carla Tully, president of AES UK & Ireland.

She explained: “It’s also about keeping the frequency of the system consistent. This is an ancillary service to enhance grid reliability.”

Tully gave an example of when the battery storage array helps to make for a more stable system.

“A few weeks ago, the electricity generated from one renewable source dropped from 500MW to just 5MW in a couple hours. That’s a huge drop. Battery storage is agnostic to where the energy comes from. That means we can charge as, and when, the wind or the solar power is ‘on’ and discharge when it’s not.”

AES’s facility at Kilroot Power Station, near Carrickfergus in Northern Ireland. Image: TechWatch

An independent body went to Kilroot and ran an assessment on the battery storage array. They said the planned expansion to 100MW could save £8.5m per year and, importantly, 123,000 tonnes of carbon emissions per year.

“Advancion has been working for eight years with more than 3m megawatt-hours of operation. There are several battery storage projects in the US, Chile, India, the Philippines and here in NI,” she said.

The first-ever battery went live in 2007 in a small project in Indiana. I wondered, could NI be a world leader in this innovation?

“We have the potential to show the world this is a reality. But the regulatory framework is needed. We need to get as much value as we can out of every wind turbine that’s installed,” Tully said.

Storage is the way forward

At the moment, frustratingly for wind farms, curtailment is used to turn off wind turbines when supply is high. Battery storage can eliminate curtailment.

Tully concluded: “We should always start with making the most of what we have. Storage is an enabler to integrate renewables in a competitive way.”

Furthermore, this project may extend the life of Kilroot Power Station for the future.

Mountains of coal at Kilroot Power Station. Image: TechWatch

By 2025, the UK has mandated that coal-fired stations will be turned off. Tully told me that environmental upgrades will allow Kilroot to operate until mid-2020. With further upgrades, this could be extended to 2023.

I was given a tour of the site in a pure-electric vehicle. We drove past the mountains of coal that are brought in by ships docked at the Belfast Lough jetty. (Currently, most of the coal is sourced in Russia and Kazakhstan, because that’s where low-sulphur coal is available). I was shown the huge machinery involved with removing the sulphur dust and NOx out of the exhaust emissions (seemingly a huge part of the plant’s operations) but CO2 is not removable.

Ken McKinley, AES’s team leader in electrical, told me that, within a few years, they hope to upgrade from the current 10MW battery array to 100MW. “That will require two buildings the size of football fields.”